Open-back recommendations

My current heaphones are starting to break down so I decided to start looking for new ones.
I have always used closed-back ones but this time I'd like to try out the open-back ones.

I know it is quite rare, but I want open back ones (or semi-open) with rich bass, since I'd like to hear what's going on around me.
I wanted to buy Audio-Technica ATH-AD700 but checked the reviews and there are 2 main problems: 1) almost no bass response at all; 2) the headphones do not seal tight over your ears.

So my requirements: good bass response (not asking for perfect, but at least good), clear mid and high frequencies, good seal over the ears, sturdy design in order to last for a very long time (this is the main reason I have to change my headphones), ability to stay on my head even if I tilt my head at least 30 degrees forward (lots of cheap ones just fall off =_=), full enclosure over the ears (to surround them completely, not to press them against the head), and plug must be 1/8" or 3.5 mm (the smaller one), since I mainly use them on my PC, where plug is in front of it - I do not want like 10cm extension. Also the resistance must be low (under 100 ohms), since I wish not to buy an amplifier for them. As well as no volume adjustment on the cord - these things always break and I have to re-solder the wire -_-
The price should (not neccessarily) be under 140 euros (120 pounds or 200 USD).

Closed back headphones normally have a bigger bass response that open back headphones - this is part of the design which like many things in engineering is a compromise.

When you fully enclose a driver (speaker) you increase bass response, this is the same principle which sees all bass response virtually disappear if you wear badly fitter In Ear Monitors which do not seal inside the ear correctly. It is the same principle which means bass speakers are often enclosed in a box to promote that low bass thump.

I have to say that although everybody hears the world a little differently open backed headphones normally have a natural and accurate bass response which very closely captures what is actually there whereas most closed backs which make a real feature of the bottom end are artificially biased towards the lower end of the frequency spectrum - the result is inaccurately bass heavy. Most open backs are very HiFi oriented which means the emphasis is on accuracy and detail and less so on fulfilling individual user desires for a particular type of EQ. Also there are very few open back headphones in the price region you indicate.

I very much agree with not having something on the cable - serious full sized headphones can last for 20 years when well looked after and additions to the cable not only degrade the sound (passive but resistant components like potentiometers) and are another thing to go wrong.

I have a suggestion for an open back which has as strong and solid bass response as any open back I have heard

Why go for open backs if they do not have the type of sound signature you are looking for? The sense of natural space in open backs is in part a direct result of venting the driver and allowing sound to leak - in essence it is created by the opposite of what creates strong bass response and EQ-ing more bass into closed backs closes down the sense of space and separation.

I would go for a more HiFi oriented Closed back - Avoid Ultrasone as these have a very open back sound until you get to the Pro and Edition ranges where they are more chunky at the bottom.

Denon have a warm and bass driven sound which is still very pretty and HiFi.

I very appreciate your time spent recommending me those.
I will take your suggestions about sticking to closed-back in consideration but I am not going to hurry - I will let myself think for a long time in order to be very sure.

I have only two questions:
1) Don't GermanMAESTRO GMP 400 Open Back Headphones (GMP400) reaally need an amplifier? It says Nominal impedance: 300 Ω.
2) Are Denon AH-D1100 Closed Back Stereo Headphones (AHD1100) silver parts made of metal? If they are, these headphones definitely look reliable in mechanical way.

Just checked the Denons for you. The Silver part of the headband appears to be metal - possibly Aluminium (or Aluminum for Americans) - but the arm which holds the ear cups is plastic. A D1100 owner might put me right on this but despite being an excellent moulding I think they are.

I have more or less decided. Only 2 of the list are left:
Denon AH-D1100
and
Audio-Technica ATH-M50

The price does not matter. What are the main differences in sound clarity and mechanical construction parts?
Actually I'm more interested in cons, rather than pros. Comparing these two would be great.
I often tend to stay with 1 ear half-lifted up (to monitor), so that puts extra strain to the headphones. Durability is a must.

The Audio Technica M50 fits this type of use much closer. They are more accurate sounding but are also intended to be used in a studio setting which is very tough on equipment. The Denons are really intended for sitting quietly in your favourite chair and are not built for a punishing time.